The invention relates to a stepwise conveying device of large objects and applies more especially to the displacement of reels in installations for the manufacture and treatment of metal bands.
In the metallurgical industry, thin sheets and strips, usually available in the form of band wound into reels, are made out of a raw product such as a slab that must be subject to various hot rolling, then cold rolling operations until the requested thickness is obtained as well as, if necessary, various treatments such as annealing, etching, skin-pass, etc.
Until recently, these operations had been carried out while causing each reel to run successively in separate installations. Each installation is then associated with an unwinder and a winder placed respectively upstream and downstream, in the running direction, whereas each reel is re-wound at the outlet of an installation in order to be transported on an unwinder situated at the inlet of the following installation.
Means for transporting the reels between the diverse treatment installations are therefore required.
On the other hand, the running speeds in the various installations are often different and it is therefore necessary to foresee storing facilities for a number of reels between two successive installations.
The reels can be transported one after the other using a travelling crane or, at floor level, by a conveying device.
Such a device comprises, usually, a series of stations for laying the reels, associated with a means of simultaneous transfer of the reels, from each laying station to the next, whereas each reel moves forward step by step from the outlet of a treatment installation to the inlet of the following installation.
Thus, a number of reels can be stored on the laying stations, between two treatment installations.
Normally, the length of band wound around a reel is several hundred meters and its weight may reach several tens of tons. A conveyor comprises, usually, four or five laying stations, which corresponds to a total load of 100 to 200 tons. If needed, several conveyors are available after one another, in order to increase the storing possibilities and the transport distance.
For several years, it has been endeavoured to realise continuous lines enabling to run the band directly from an installation to the next, but the possibilities are limited and there are still separate installations that call for a transport of the reels over a certain distance.
Generally, a stepwise conveyor comprises a fixed series of laying stations distributed along a longitudinal displacement direction and centred on transversal planes spaced apart by a constant pitch and a mobile series of recovery stations spaced by the same pitch and arranged on a longitudinal supporting beam, mobile on the one hand vertically, between a lowered position and a raised position for which the recovery stations are placed, respectively, below and above laying stations and, on the other hand, longitudinally, between a retracted position and a forward position for which each recovery station is centred, alternately, on the transversal planes of two successive laying stations.
Thus, in the retracted position of the beam, the recovery stations are placed below the laying stations and centred on the same transversal planes as the laying stations. Lifting the beam assembly up to its raised position therefore enables each recovery station to take charge of the reel placed on the corresponding laying station.
The supporting beam is then brought forward by a single step while moving the set of reels above the ground, whereas each recovery station is placed above the following laying station. Lowering the beam enables to lay the reels on the corresponding laying stations. The beam thus unloaded may then return to its initial retracted position, whereas the recovery stations run below reels placed on the fixed laying stations.
Usually, the laying stations are each composed of two bearing sections arranged on the floor, provided on either side of a trench in which the longitudinal supporting beam is placed, whereas each recovery station is thus located between both bearing sections of the corresponding laying station.
These recovery stations are necessarily rather narrow and the vertical and horizontal displacements should be performed without any jerks to avoid any risks of a reel, whose weight may exceed 20 tons, losing its balance and falling down.
Since the conveying device must be able to store several reels, the total load supported by the beam may be in the order of 100 to 200 tons. A beam capable of supporting such a load must obviously be sufficiently rigid and have, in particular, quite a significant height to sustain deflection.
On the other hand, the supporting stations are relatively narrow and the beam should move parallel to itself, while remaining perfectly horizontal, to preserve the balance of the reels. To this end, deformable parallelepiped systems are used normally, comprising at least two sets of rods whose rotation is controlled by actuators to determine the lifting and the lowering of the beam. The rods should not be arranged in a straight position, but slightly tilted at the onset, in the lowered position of the beam. Such systems are therefore rather cumbersome and increase the total height of the device.
The purpose of the invention is to remedy these shortcomings and solve all the problems that have just been exposed thanks to a new conveying device, particularly simple and cheap that enables, quite safely, stepwise displacement of massive and very heavy objects such as metal reels.
According to the invention, the supporting beam of the recovery stations rests on the floor by means of at least two sliding bearing members, of adjustable height, extending vertically over at least a portion of the height of the beam and comprising, respectively, at least two actuators to adjust the level of the synchronism operated beam and associated, respectively, with at least two sliding guiding means of the supporting beam enabling longitudinal reciprocating displacement of the said beam, respectively in a forward direction in raised position and in a retraction direction in lowered position, whereas each actuator comprises two elements, respectively fixed and mobile, bearing in opposed directions, respectively on the beam and on the floor.
In a particularly advantageous fashion, the level adjustment actuators of the beam are hydraulic jacks associated with a feeding system at constant flowrate, identical for all jacks, in order to keep the beam horizontal during its displacements, regardless of the distribution of the load.
As stated above, indeed, the supporting beam must sustain the load of several reels and comprises, to this end, a horizontal sole on which are mounted the recovery stations and at least one vertical stiffening girder with sufficient height for the beam to remain rigid under the load of the transported objects. In a particularly advantageous fashion, the adjustment actuators extend over at least a portion of the height of the girder, in the lowered position of the beam so that the total height of the device is of the same order of that of the beam.
In a preferred embodiment, the longitudinal beam exhibits, as a transversal cross-section, a reverted U shape comprising a substantially horizontal upper portion, forming a sole for the recovery stations and two substantially vertical wings, forming stiffening girders of the beam and, in the lowered position of the said beam, at least the level adjustment actuators are accommodated inside the beam, between both wings.
In a particularly advantageous embodiment, each sliding bearing member comprises a supporting carriage composed of a chassis resting on at least one longitudinal guiding rail by means of two running gears spaced longitudinally and on which is mounted at least one hydraulic actuator for level adjustment of the supporting beam.
In particular, the carriage can be supported by two axles spaced longitudinally, on either side of a central section of the chassis forming a bearing platform of a hydraulic adjustment actuator having one element fixed on the platform and one mobile element resting on the beam.
According to another particularly advantageous feature, the beam is connected, in vertical displacement, with the mobile elements of the actuators and the supporting carriages of the actuators are maintained against the guiding path by an anti-rise means opposing the lifting motion of either of the supporting carriages with respect to the guiding path. To this end, the supporting carriages can be connected advantageously, in the longitudinal direction, by at least one linking bar composed of a structural bar having at least one sole passing below at least two anti-rise rollers, spaced longitudinally.
In a first embodiment of the invention, the assembly composed of each supporting carriage with its running gears and the adjustment actuator, is not as wide as the space between both wings of the beam in order to rest at least partially in the said space, in lowered position of the beam.
In a second embodiment, each supporting carriage comprises a chassis placed between both wings of the U-shaped beam and resting on both guiding rails by means of two running gears spaced longitudinally and each containing a pair of wheels placed outside the beam and mounted at two extremities of an axle running through a bore into the chassis and traversing both wings of the beam while running through oblong holes provided in the said wings and each of sufficient height to enable vertical displacements of the beam between the lowered position and the raised position.
Advantageously, the width of each oblong hole through which runs the extremity of an axle, is substantially equal to the diameter of the said axle in order to form a connection means, in the longitudinal direction, of the beam with the corresponding supporting carriage.
The alternating longitudinal displacement means of the beam can be composed of at least one hydraulic actuator with a first element resting on a fixer section and a second element resting on a section integral with the beam, in longitudinal displacement.
However, since the level adjustment actuators determine perfectly vertical displacement of the beam, there is practically no horizontal reaction to be compensated for. Consequently, the longitudinal displacement means of the beam can be composed of a cable running over two intermediate means placed at two extremities of the guiding path and having two belts fixed respectively at both extremities of the supporting beam, whereas the said cable is driven into two opposite directions to control, respectively, the forward motion and the retraction of the beam.